Indicators



Dec. 2, 1969 P. D. WILLIAMS INDICATORS Filed Sept. 5, 1968 FIG. IA

FIG. 2A

FIG. 2B

INVENTOR. PETER DOUGLAS WILLIAMS ATTORNEY 3,481,304 INDICATORS Peter Douglas Williams, Haddenlram, England, assignor to Honeywell Limited, Brentford, England, a British company Filed Sept. 3, 1968, Ser. No. 756,821 Int. Cl. G01] 19/12 US. Cl. 11670 Claims ABSTRACT OF THE DISCLOSURE A fluid operated indicator is disclosed which comprises a piston within a cylinder, the piston being divided transversely into two portions, and the cylinder having a window in its side. Two visually distinct parts of the piston may be alternatively presented at the window by positioningthe whole piston at one end, or the other, of the cylinder, or the two piston portions may be positioned at opposite ends of the cylinder so that neither of the visually distinct parts appears atthe window. Thus the indicator may be placed in three different conditions, the third one of which may be employed merely as reset condition or else as a third positive indicating condition.

This invention relates to indicators, and particularly to fluid operated indicators.

The present invention provides a fluid operated indicator comprising a cylinder closed at both ends, a piston fitting within the cylinder, a fluid inlet at each end of the cylinder, a window at the side of the cylinder and at at distance from each end of the cylinder, the piston having two visually distinct parts which are alternatively .visible at the window when the piston is positioned at one United States Patent 0 end or the other of the cylinder by a differential fluid I The two parts of-the piston may be made visually distinct"in any way'which results in their appearances w through the windowbeing clearly diflerent. For instance, they may be painted with differently coloured luminous paints.

From a further aspect of the invention, however, at least one of the two visually distinct parts of the piston carries a symbol which 'is adapted to co-operate with a further symbol or symbols presented adjacent to said window, when the piston is so positioned as to make the symbol on it visible at said window.

For other applications .it maybe convenient for the two visually distinct parts of the piston to carry different symbols which are adapted to co-operate differently with a further symbol or symbols presented adjacent said window, when the piston is so positioned as to make the respective symbols on it visible at said window.

The further symbol or symbols may then conveniently be presented on a face plate of the indicator.

In order that the invention may be more clearly understood, two embodiments of it will now be described, by way of example, with reference to the accompanying drawings in which:

FIGURE 1 shows basic features of an indicator in which the piston has differently coloured parts,

FIGURE 1A shows the further features which are provided in accordance with the invention to improve the indicator shown in FIGURE 1,

3,481,304 Patented Dec. 2, 1969 FIGURES 2A and 2B show different positions of a further indicator in which the piston and face plate of the indicator carry symbols, and it will be appreciated that the features shown in FIGURE 1A may also be applied to this type of indicator.

Referring to FIGURE 1 there is shown an indicator according to the invention which comprises a cylinder 1 which is closed at both its ends 2 and 3. At the ends of the cylinder 1 there are respective fluid inlets 4 and 5.

In the side of the cylinder 1 there is a window in the form of an opening 6 which is a little less than one third as wide as the cylinder is long. In practice the window 6 will be covered by a transparent material to keep dirt out of the indicator but in principle this is not essential. In FIGURE 1 the lower half of the front of the indicator is shown cut-away for the sake of clarity, but, in fact, the lower half of the front of the indicator will be the same as the upper half.

A piston 7 fits within the cylinder 1 and its length is two-thirds of that of the cylinder. The piston 7 is divided into two visually distinct parts 8 and 9, for instance, by painting the respective parts different colours with luminous paints.

In use, the inlets 4 and 5 are coupled in any suitable manner to respective sources of fluid pressure and it will be appreciated that the piston 7 can then be positioned at one end or the other of the cylinder 1 by applying a pressure differential between the inlets 4 and 5 in the appropriate direction. Thus by changing the direction of the applied differential pressure either the part 8, or alternatively the part 9, of the piston 7 can be made visible at the window 6. g

The modification according to the invention is illustrated separately in FIGURE 1A. This consists in dividing the piston transversely to its direction of movement, for instance (though not necessarily) along the line separating the parts 8 and 9 in FIGURE 1, into two portions and providing a further fluid inlet which is capable of conducting fluid to between the two portions even when the piston is at either end of the cylinder. This can be arranged, as shown, by having a central inlet 15 which leads into a longitudinal channel 16 in the cylinder wall, the channel 16 extending sufiiciently far towards each end of the cylinder for the division between the two piston portions to always be adjacent to it.

By adopting the feature just described, one is able to test whether or not a differential pressure is being supplied to the indicator by temporarily applying a suitably high pressure fluid to the further inlet 15. This will drive the two piston portions apart so that they lie at opposite ends of thecylinder. If a differential pressure is present, they will return'to their original position, whereas if it is not they will stay at the respective ends of the. cylinder. If the application of a suitably high pressure to the further inlet 15 will not part the piston portions, this will indicate some defect in the indicator. If the indicator is mounted with the cylinder horizontal, a pressure can be applied temporarily to the further inlet to drive the piston portions to the ends of the cylinder where they will remain until a differential pressure is applied in one direction or the other to the end inlets, thus allowing the indicator to be reset to a condition where it gives no positive indication until some differential pressure is applied across its end inlets. It will be appreciated that if the interior of the cylinder is made highly light-absorbent the condition with the piston portions apart will result in the window appearing black, so that the indicator could be used to give three diflerent and distinguishable indications when supplied with suitable input signals.

The ends of the piston portions could be provided with small projections so as to facilitate the penetration of the fluid between the two portions, or between either portion and the respective end of the cylinder 1.

Referring to FIGURES 2A and 2B of the drawings these show two different conditions of a further indicator according to the invention which has a flat face plate 10 which may be moulded integrally with the cylinder body. The face plate 10 carries a symbol 11 which may represent, for example, a pipe, and a further symbol 12, at right angles to the symbol 11, representing a further pipe.

The piston 7 carries on one part a vertical symbol 13 which when the piston 7 is at one end of the cylinder 1 co-operates with the symbol 12 on the face plate 10 to form a complete vertical line. The other part of the piston 7 carries a horizontal line 14 which when the piston 7 is at the other end of cylinder 1 co-operates with the symbol 11 to form a complete horizontal line.

An indicator such as is shown in FIGURES 2A and 2B may be incorporated into the front of a control panel to form part of a schematic representation of an industrial plant of which the pipes repres nted by symbols 11 and 12 form parts. The fluid inlets 4 and 5 can then be coupled by means of suitable transducers to the actuating mechanisms of valves located in the two pipes so that when the valve in the pipe represented by symbol 12 is opened and that in the pipe represented by symbol 11 is closed the indicator appears as shown in FIGURE 2A, whereas it appears as shown in FIGURE 2B when the valves are operated in the opposite sense. In this particular application the indicator will then show diagrammatically which of the pipes is open and which of the pipes is closed.

It will be appreciated that FIGURES 2A and 2B show only a single example of an indicator according to the invention in which symbols on the piston co-operate with symbols adjacent the window, and that many other types of symbols may be devised for other purposes.

Where the piston carries symbols, it will usually be necessary to prevent the piston from rotating within the cylinder, so as to keep the symbols properly positioned, and this can be done by making the cylinder and piston non-circular (for example oval) in cross-section or providing suitable guides which prevent rotation of the piston. In general, of course, there is no reason why the piston should have a circular cross-section.

Furthermore the actual construction of the indicator may differ from that shown in FIGURES 1 and 1A, for instance it would be possible to enclose the piston in a transparent cylinder and mount the transparent cylinder behind a mask or within a casing which contains an aperture to provide a window 6.

In order to allow the indicator to be miniaturised as far as possible and yet still to give an easily visible indication the window 6 may be provided with a magnifying lens.

Although in the embodiment described with reference to FIGURES 1 and 1A the piston is two-thirds of the length of the cylinder and the window 6 has a width which is a little less than one-third of the length of the cylinder, these relative dimensions are not essential although they do make for a particularly compact construction. In principle the indicator will operate provided that the piston can move sufiiciently far, relative to the width of the window, for its two visually distinct parts to be made visible at the window one at a time.

The embodiments described are intended to be illustrative only, and the invention is not to be limited except by the scope of the appended claims, in which I claim:

1. A fluid operated indicator comprising a cylinder closed at both ends, a piston assembly within the cylinder, a fluid inlet at each end of the cylinder, a window at the side of the cylinder and at a distance from each end of the cylinder, the piston assembly having two visually distinct parts which are alternatively visible at the window when the piston assembly is positioned at one end or the other of the cylinder by a differential fluid pressure applied between said inlets, the piston assembly being divided, transversely to its direction of movement, into two discrete portions, a longitudinal recess portion formed in the interior wall of said cylinder, a further fluid inlet being provided in said cylinder in fluid communication with said recess portion, the recess portion being of such an extent that fluid entering said further inlet is capable of being conducted between said two discrete portions regardless of the position thereof in the cylinder, whereby the two portions can be driven apart by application of a sufficient fluid pressure at the further inlet.

2. An indicator according to claim 1 in which at least one of the two visually distinct parts of the piston assembly carries a symbol which is adapted to co-operate with a further symbol or symbols presented adjacent to said window, when the piston is so positioned as to make the symbol on it visible at said window.

3. An indicator according to claim 1 in which the two visually distinct parts of the piston assembly carry different symbols which are adapted to co-operate differently with a further symbol or symbols presented adjacent said window, when the piston assembly is so positioned as to make the respective symbols on it visible at said window.

4. An indicator according to claim 2 in which the further symbol or symbols is or are presented on a face plate of the indicator.

5. An indicator according to claim 3 in which the further symbol or symbols is or are presented on a face plate of the indicator.

References Cited UNITED STATES PATENTS 522,995 7/ 1894 Maxim 73--208 1,483,200 2/1924 Skold 73208 2,526,568 10/ 1950 Leonard 184-7 2,575,982 11/1951 Stevens 92-62 XR 2,948,151 8/1960 Astl 73-406 2,970,561 2/1961 Ashwood 116117 3,182,630 5/1965 Claeys 116--70 3,208,425 9/1965 Jousma et al. 116-34 3,300,769 1/1967 Batur.

LOUIS I. CAPOZI, Primary Examiner US. Cl. X.R. 

